The primary objective of the proposed study is to document the transport mechanics, dispersal patterns, and distribution of mercury and other trace elements in the Lahontan Reservoir that resulted from mining and milling of the Comstock area. The investigation is designed around the development of conceptual and mathematical models describing the dispersal of mercury. The Carson River/Lahontan Reservoir system provides an excellent setting for model development because the primary sources of mercury are known, it exists at analytically detectable levels, and mercury is associated with both amalgam particles and other particulate matter allowing the modes of contaminant transport to vary significantly. The models will be based on geomorphic, sedimentologic, hydrologic, and chemical data collected to determine: (1) spatial and temporal variations in mercury loading of Lahontan Reservoir, (2) the vertical and lateral distribution of mercury in the reservoir's bed materials, (3) the relations between mercury concentration, form, and sedimentary facies, (4) the flux of dissolved mercury from contaminated sediments, and (5) the chemical speciation of dissolved mercury in the water column. Once developed, the models will be used to assess the future dispersal and fate of mercury in the Carson River Valley and, in addition, their applicability to the dispersal of other potentially toxic trace elements. The investigation will not only supply information necessary for site remediation, but provide an understanding of the physical and chemical environment vital to biologic and epidemiologic studies.